Micro-Bose/Proca dark matter stars from black hole superradiance

TL;DR

This paper explores how primordial black holes can produce dense, long-lived bosonic dark matter stars through Hawking evaporation and superradiance, potentially accounting for a significant portion of dark matter.

Contribution

It introduces a mechanism for forming dense bosonic dark matter stars from primordial black holes via superradiance and Hawking evaporation, highlighting their potential to make up a large fraction of dark matter.

Findings

Superradiance can produce dense bosonic dark matter stars from primordial black holes.

These dark matter stars can survive until today, constituting over 50% of dark matter in some cases.

The resulting objects are extremely compact, with radii less than a picometer.

Abstract

We study the production of heavy, $\mu \gtrsim 1$ TeV, bosonic spin $s=0,1$ dark matter (DM) via the simultaneous processes of Hawking evaporation and superradiance (SR) from an initial population of small, $\lesssim 10^6$ kg, primordial black holes (PBHs). Even for small initial PBH spins the SR process can produce extremely dense gravitationally-bound DM Bose or Proca soliton "stars" of radius $\lesssim {\rm pm}$ and mass $\sim 10^{\rm few}$ kg that can survive to today, well after PBH decay. These solitons can constitute a significant fraction of the DM density, rising to $\gtrsim 50\%$ in the vector DM case.